Aggregation for any UI element within a tab.
You can create this aggregation in the View Designer in the UI tree from the context menu (entry Insert Element in Tab).
Aggregation for a tab title, which is implemented using a Caption UI element.
Tab Captions cannot be used as a drag handle, Drag&Drop.
You can create this aggregation in the View Designer in the UI tree from the context menu (Insert Header).
Aggregation for a Toolbar within the tab.
You can create this aggregation in the View Designer in the UI tree from the context menu (Insert Toolbar).